albert schmidt



A. SCHMIDT.

SPARK PLUG AND METHOD OF FORMING THE SAME.

APPLICATION FILED FEB-1.1915.

Patented Aug. 1, 1916.

fl A//A IIVVE/VTOR 1 A TTORNEVS UNITED STATES PATENT OFFICE. Y

ALBERT SCHMIDT, OF FLINT, MICHIGAN, ASSIGNOItTO CHAMPION IGNITION COMPANY,

OF FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

SPARK-PLUG AND METHOD OF FORMING THE SAME.

To all whom it may concern Be it known that I, ALBERT SoHMIp'r, a citizen of the Republic of France, residlng at Flint, in thecounty of Genesee and State of Michigan, have invented certain new and useful Improvements in Spark-Plugs and Methods of Forming the Same, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to the manufacture of spark plugs and particularly to the construction and method of forming the same by which a sealing joint between the insulator and casing is maintained iegardlem of the temperature to which the plug is subjected.

In the drawings: Figure 1 is a longitudinal section through the insulator and casing before the sealing joint is formed; Fig. 2 is a similar view showing the manner of clamping the insulator against the sealing gasket, and at the same time electrically heating and fashioning the metal of the case; and Fig. 3 is a similar view of the completed plug, partly in elevation.

A is the insulator which is provided with the usual electrode B passing therethrough, and with the annular enlargement C for seating in the casing I). This casing is formed with ashoulder E, against which one face F of the enlargement C is seated, a compressible and resilient gasket G formed of copper, asbestos or other suitable material being placed therebetween. To secure the insulator in the casing and to hold the -face F against the gasket G at all times with sufficient pressure to maintain the seal, and without regard to the temperature of the plug, I proceed as follows: An initial pressure is first placed upon the gasket, preferably by'placing the casing D in a bearing H and applying pressure to the outer face of the insulator A by a clamping member I. This compresses the gasket so as to form a perfect seat and a sealing joint. The case D is then closed in, so as to bear upon the opposite face J of the enlargement C, and

the metal of the casing is simultaneously heated to' expand the same, whereby in Specification of Letters Patent.

Patented Aug. 1, 1916.

Application filed February 1, 1915. Serial No. 5,386.

cooling the contraction of the metal will further increase the pressure on the gasket. This operation is preferably performed by an electric heating apparatus and as shown the member H forms one electrode of this apparatus and a member K the other electrode, which latter bears against a thin flange L at the upper end of the casing. When current is supplied to the electrodes the resistance at the point of contact between the fiange L and electrode K .will heat the metal until it becomes plastic, and by forming the electrode K as a die and applying pressure thereto the softened metal may be closed about the insulator, as shown in Fig. -3. I preferably place a gasket M, of copper or other suitable material, between the insulator and the plastic metal, so as to more uniformly distribute the temperature and to avoid cracking of the insulator. The heat applied to the metal of the casing will expand the same, and therefore upon cooling contraction will take place, which will still further increase the pressure upon the gasket G. Furthermore, as the heating of the case during this operation is greatly in excess of any heat imparted thereto when the plug is in use, the seal will be maintained at all times. In other words, the resiliency of the gasket and of the metal of the case is such that when the parts are cooled they are placed under a tension, and upon the reheating of the parts the expansion is fully compensated for by the resilient tension.

What I claim as my invention is 1. The method of forming spark plugs, comprising the seating of the insulator in a casing or bushing upon a compressible, resilient' gasket, applying an initial pressure against the insulator to compress said gasket, heating the metal of the casing to substantial plasticity, and fashioning the same While heated to substantial plasticity to bear against said insulator and to maintain the pressure upon said gasket.

2. The method of forming spark plugs, comprising the seating of the insulator in a casing upon a compressible resilient gasket, compressing the gasket between the insulator In testimony whereof I affix my signature 1n presence of two Witnesses.

ALBERT SCHMIDT.

Vitnesses JAMES P. BARRY, HENRI E. BOWMAN. 

